Henoch-Schönlein Purpura (IgA Vasculitis): Clinical Manifestations
Henoch-Schönlein purpura presents with a characteristic triad: non-thrombocytopenic palpable purpura predominantly on the lower extremities and buttocks, arthritis or arthralgia, and abdominal or renal involvement. 1, 2, 3
Primary Cutaneous Manifestations
- Palpable purpura is the hallmark skin finding, appearing as non-blanching, raised purpuric lesions that do not resolve with pressure 1, 2, 3
- The rash characteristically affects the lower extremities and buttocks, though it can extend to other areas 1, 4, 5
- Skin lesions may initially present as papules or urticarial lesions before evolving into purpura 4
- Hemorrhagic bullous lesions can develop in severe cases, though this presentation is rare and may lead to scarring or hyperpigmentation 1
- The purpura is non-thrombocytopenic, meaning platelet counts remain normal despite the bleeding into skin 3, 5
Musculoskeletal Symptoms
- Arthritis or arthralgia occurs in the majority of patients, typically affecting large joints 2, 4, 3
- Joint involvement is usually transient and non-deforming 4, 5
- The knees and ankles are most commonly affected 4
Gastrointestinal Manifestations
- Abdominal pain is a frequent presenting symptom, occurring in a substantial proportion of patients 2, 4, 3
- Gastrointestinal bleeding can occur and may be life-threatening in severe cases 4, 3
- Symptoms may include nausea, vomiting, and colicky abdominal pain 4, 5
- Abdominal manifestations can precede the characteristic rash, making early diagnosis challenging 4
Renal Involvement
- Nephritis develops in a subset of patients and represents the most significant long-term complication 3, 5
- Renal manifestations include hematuria, proteinuria, and varying degrees of kidney dysfunction 3
- Glomerulonephritis can persist and relapse years after initial presentation, necessitating prolonged monitoring 3
- The extent of renal involvement determines long-term prognosis 3, 5
Additional Clinical Features
- Central nervous system involvement can occur as a rare complication 3
- Orchitis (testicular inflammation) may develop in male patients 3
- The disease is most common in children but can affect adults, with slightly different clinical patterns 4, 3, 5
Diagnostic Considerations
- Skin biopsy reveals leukocytoclastic vasculitis with IgA deposits in vessel walls on direct immunofluorescence, confirming the diagnosis 1
- Laboratory testing shows normal platelet counts despite purpura, distinguishing HSP from thrombocytopenic purpura 3, 5
- Any component of the classic triad may be absent at presentation, which frequently delays diagnosis 4, 5
Clinical Pitfalls
- The rash may not appear initially, with arthritis or abdominal pain presenting first, leading to misdiagnosis 4, 5
- Hemorrhagic bullous variants can be mistaken for other severe dermatologic conditions 1
- The disease is often preceded by upper respiratory infections, particularly group A streptococcal infections, though this association is not universal 5
- Other triggers include food reactions, cold exposure, insect bites, and drug allergies 5